Cam-operated shaft straightening device



March 25, 1958 E. E. JUDGE, JR 2,827,943

CAM-OPERATED SHAFT STRAIGHTENING DEVICE Filed March 9, 1953 INVENTOR Zw/mw f (/0065 Me.

ATTORNEY motive cam-shafts and crankshafts.

United States Patent CAM-OPERATED SHAFT STRAIGHTENING DEVICE Edward Earl Judge, Jr., Lansing, Mich, assignor to ,In-

dustrial Metal Products Corporation, Lansing, Mich., a corporation of Michigan This invention relates to a shaft straightening device and a controlling mechanism therefor. More particularly, this invention relates to an hydraulically actuated straightener of .the type employing a hook 'mounted on an eccentric so that rotation of theeccentric impart-s ventical movement to the hook,thereby deflecting. a 'shaft, and control means therefor.

Wherever shafting is produced there and misalignments which must be removed prior to the application of the shafts to the purposes 'fOr which they were designed. Typical examples are various forged auto- The removal 0f "the misalignment in such shafts must be accomplished by machines capable of extreme precision under extreme pressures. Heretofore, owing to the difliculties in predetermining the extent of sha'ftdeformity, machines :capable ofstraightening such shafts have operated on a cut :and dry basis at a sacrifice of manyman-hours and-with non uniform results. Operator skill played a predominant role in the accuracy obtained and relatively few operators have mastered a the feel of machine and stock lnecessary Where machines incapable in positive precision :adjustments in corrective deformation have been used.

My present invention permits more accurate :shaft straightening, greater machine life, :and .increasedwoptimum ranges of pressure.

Accordingly, it is the purpose of this invention to-provide a hook type hydraulic shaft straightening machine capable of being equipped with controls of sufficientia'ccuracy, precision, and simplicity to make for more .rapid operation wtih continual high quality results.

A further object of .the invention .is "to provide a :mechanical-electrical-hydraulic control system which may the simply adjusted by realtively .unskilledoperators so .that a setting of the controls will result in :a .knowncorrective deformity imparted by the machine to .the-shaftsto' be straightened. A rotating hydraulic cylinder movesfan eccentric which imparts vertical movement to awhook, the vertical movement being translated mechanically to activate an electrical circuit, theelectrical circuit controlling an hydraulic circuit which energizes the rotating shydraulic cylinder to permit travel 'of the .hook 1a predetermined distance and then automatically returns .the hook to its starting position allowing .a pause during which the shaft to be straightened is under azero deflection load; During this pause .the operator .is permitted to read dial indicators which accurately show .the-effect of the stresses upon the shaft and to select 'bytrotation of the control knob *an amount of :machine deformity to .act as acorrective in-thenextcycle.

A further object is toceliminate the :complexarrangement of circuits heretofore requiredto control-geardriven mechanisms.

.A further object .isito provide a mechanism of operating simplicity combining readily accessible ,parts for .maintenance. 1 g

A further .object is tto .reduce .the operative partsjn number and complexity to provide a mechanism of are irregularities ice cheaper construction which does not sacrifice precision results.

'Other objects and purposes of the invention will become apparent to persons acquainted with this type of op paratus upon a study of theaccompanying drawing and a d'eadingofthe following specification.

"In the drawing:

1 Figure '1 represents :a schematic front elevation of the :s'haftstraightener.

Figure 2 represents a partial cross-section of a preferred embodiment of my straightener mechanism showing the mechanical control linkage.

Figure 3 .is a circuit diagram showing the electrical .components of the control circuit.

Figure '4 is an hydraulic circuit diagram showing the hydraulic components in the hydraulic control circuit General description 'IjIIl general; my improved straightening machine includes ia.-tableaor irameihaving a pair of shaft supports on the uppensidetthereof, -andopening through the top of said :tablmbetweenv said shaft supports, a hook attached .to apitmamarm operating an :of an eccentric located di- -rectlybeneath ithe :openingyin said table; the hookextend- .ingupwardly.throughpaid opening'in the table. To the eccentric :isroperably attached, arotating hydraulic cylinder in such .manner as toaimpart notation to said ec- .centric, "which rotation is translated .torlineal up .andzdown motion. Thisiineahmovement is transmitted tothehook sand .thehook :imparts corrective deformation to 4 the :shaft '10 be ,-strai ghtened. A mechanical linkage attached to :the main shaft to whichthe eccentric is connected causes .a pin .to .be displaced by a distance proportionalitonthe hook movement. The ,pins movement is such as to displace a cam which is rotatably mounted 2on1.the .adiust- -ing..knob shaft. Rotation .of the cam by the operator varies .the gap between the .camand -the;pin. As the cam :is moved by the pin a drive switch, closed while .thfirhOOk .isaunder load, is. opened. When this switchdstopened-the .solenoid of an hydraulic control valve .is deenergized and .the hydraulic drive circuit is reversed causing the rotating .hydraulic cylinder to return to itsoriginal position against vane stops built into the rotating cylinder. .rotating hydraulic cylinder resumes its original position When the a second switch is closed permitting the. cycle to be re- ;peated when the operator by pressure upon the control .knob closes the first mentioned switch. The original posi- .tion of. the rotating hydraulic cylinder is such that the .to read dial indicators for showing the run-out on the shaft to be straightened and permitting the operator to select an amount of corrective deformation on the next 'cycle indicated bythe dial reading.

Specific description Referring more particularly to thedrawing, wherever directions are referred to thedirection shall be given with reference to the .schematicldiagram :in frontelevation as indicated in Fig. 1. Thus upwardly shall .have reference to a directionrelative to the top ,of the device as there shown and downwardly shall .havereference directionally toward the 'base of the device as .there indicated. The shaft straightener substantially comprises a table 11 upon the top of which are mounted shaftsupports 12. The shaft supportsrjlz are schematicallyshown and other varieties may be used depending upon the nature of the shafts to be straightenedlS and other holding considerations. Substantially near the centerofithe table 11, and in its top 14, is located anopening 15.which permits-movement of-a downpulling hook lfi'hoth vertically when straightening shafts 13, or rockably as when brought into engagement over a shaft to be straightened The hook 16 is detachably and adjustably fixed .to a pitman 17 which operates oifof the e'ccentric17a keyed to the main shaft 18. The main shaft 18 is aligned with the shaft to be straightened 13, but is beneath thev table top 14. The main shaft 18 is'connected, asby keys=or splines (not shown), so as vto be rotatable by a rotating 19, the hook 16 is made to reciprocate. A downpulling force is therefore applied to the hook 16 which provides the desired downward pressure upon the shaft to be straightened 13.

'At this point it should be understood that a plurality of'hooks 16 operating off ofa plurality'of eccentrics 17a 7 upon the main shaft 18,'which main shaft 18'is.driven by a single rotating hydraulic cylinder 19 as comprehended by the spirit of this invention. The unit as herein described is duplicated upon a'commonshaft 18 with individual controls for each hook 16. Only one hook 16 Y is engaged at a time with the shaft to-be straightened 13, the others reciprocating upon their eccentrics 17a, but not engaged with the shaft to be straightened 13, unless so desired. Elimination of the main shaft 18 is possible where the rotating hydraulic cylinder 19 is connected 7 directly to the eccentric 17a. In the precise embodiment shown, the eccentric 17a is keyed to the main shaft 18 but the main'shaft 18 might satisfactorily comprise a crankshaft to accomplish reciprocation.

Referring to Fig. 2, a connecting link '23 is pivotally and eccentric'ally connected to the end of the main shaft 18 and at its other extremity connected pivotally toa lever link 24. The lever link '24 is one arm of a lever 25 which pivots about the axis of the pivot shaft 26. i The pivot shaft 26 is suitably journaled in the structural portion of the table 11. The lever 25 is provided at its terminal end with an adjusting screw 27. The location of the adjusting screw 27 is such as to bear upon the lower end of a pin 28 capable of'vertical movement but'restrained from lateral displacement by the jacket 29, the jacket 29 being fixed to the table 11. Inside'the jacket 29 is a spring 30 whichurges the pin 28 downward, the spring 30 being restrained at the upper extreme by the jacket 29 and at the lower extreme by the pin collar 31. It has been found that the pin 28 performs equally well Without the spring 30, the collar 31 providing a stop retaining the pin 28 from falling clear ofthe jacket 29 and gravity urges the pin 28 downward to engage the adjusting screw 27. The upper end of the pin 28 is capable of moving into engagement with a cam 32 fixed to the adjusting knob shaft33. The adjusting knob shaft 33 is retained in and rotatable in the adjusting frame 34 and is provided with. an adjusting knob 35 with a pointer in dicator. The adjusting frame 34 is pivotally mounted at pivot 36 upon a pedestal bracket [37. The pedestal bracket 37 is firmly attached to a structural part of the 'tablell. Atthe top of the adjusting frame'34 is a clevis connection 38. A spring clevis 39 is pivotally connected at its extremes between the clevis connection 38 upon the adjusting frame 34 and the clevis mount 48. The clevis mount 40 is fixed to the pitman arm 17. The ,springjclevis 39 is resiliently designed by providing a threadable ad;

'justable rod 42 which acts against a clevis spring 43 within a sleeve 44. The spring clevis.39 provides means whereby the hook 16 may be pulled into engagementover or'released from engagement over the shaft to be straightened v 13 when, the adjusting knob 35 is pulled forward and downward or upward and backward upon the adjusting knob pivot 36.

The adjusting knob 35 is arranged to engage the hook 16 over the shaft to be straightened 13. The adjusting frame 34, when the adjusting knob shaft 33 reaches the horizontalposition, seats against the bracket 37 which is connected to a portion of the table 11. A threadably adjustable switch trip 45 is provided in the base part of the adjusting frame 34 to engage the drive switch-46 of the normally open variety. The positioning of the switch trip 45 is such as to close the drive switch 46 when'the adjusting knob 35 is held down by. the operator against the pedestal'bracket 37. A limit switch 47, closed when the straightener is in the original or starting position, is located and conveniently mounted upon a part of the table 11. This arrangement permits the limit switch 47 to ,be engaged by, a member in the lever group operating .oifof the main shaft 18 and the'pivot shaft 26. A preferred arrangement places the limit switch 47 in contact withthe lever 25 when the shaft straightener isrin the a conventional practice to assure a high degree of pro tection to operators handling machinery of this type.

Other voltages may be similarly satisfied by modifications in the circuit. The three line leads 48,49 and 50 are provided with a master switch 51., A motor starter 52 is interposed upon the 220 volt circuit between the master switchand the motor 53 to which the leads 48, 49 and 50 are terminally. connected. A transformer 54 is provided to supplyqener'gy to the, volt control circuit. On either sideof the transformer 54 are located fuses 55 and 56. Motor overloads 57 are likewise provided which are normally closed inthecircuit. A start-stop switch 58 .is inserted in the 110 volt control circuit. The particular start-stop switch 58 preferably used is provided with. a green light indicator 60 which indicates that the electric hydraulic 'drive'is'functioning. The green light indicator 60'is not operative 'untilrthe normally open start button on the start-stop switch 58] is closed or pushed. By closing the. start-stop switch 58 the normally open magnetic motor starter why 59 is closed at contacts 59a, 59b and 59c and the electric motor 53 is energized which in turn drivably rotates: the hydraulic pump 61. The relay 59 also closes the shunt around the startbutton at contact 59e and closes .fcontact 59d preparing the remainder of the control circuit forfenergization. The pushing of the start button of the start-stop switch 58 thus starts the vflow of hydraulic fluid through the hydraulic circuitand therotation of the rotating hydraulic cylinder 19 is only such as to lo'catethe eccentric 17a and the hook 16 in the startingposition the rotation of the rotating hydraulicicylinderibeing halted against the vane stop 22 also closed because the hook 16 is in the original or 'start position, the'magnetic relay 62 is energized closing the shunt 63 at conta'ct point 62a around the limit switch 47 and closing the circuit to the solenoid 64 at contact point 62b. Thesolenoid 64 shifts the hydraulic circuit from return position to drive ,position. The solenoid 'accomplishes this shift .by directing the flow ofhydraul c fluid through a four-way pilot valve 65 so that the four- .32 and pin 28. When the pin 28 engages and moves the cam 32 the drive switch 46 is opened, the magnetic :relay 62 is de-energized .and the circuit to the solenoid 64 is broken. The pilot valve .65, aside from being solenoid operated, is provided with a spring return 68 and the breaking of the circuit to the solenoid 64 reverses the flow in the pilot lines automatically reversing the flow in the drive circuit through the control valve 66 and the rotating hydraulic cylinder 19 is thereby reversed until the rotating vanes 69 inside the cylinder 19 are brought up against the vanestop 22 which is built into the cylinder 19. The substitution of a straight hydraulic cylinder is possible by an adoption of rack and pinion means but mechanical failures are avoided and simplicity better obtained with the rotating type cylinder 19. A pressure .relief valve 70 in the hydraulic return line provides a clump to the tank or reservoir 71 if the pressure in .the lines builds up beyond the operating limits required to return the hook 16 to its original position. The positioning of the .va'ne stop 22 in the rotating hydraulic cylinder 19 coincides with the starting .position of the hook 16 somewhat above the shaft to be straightened 13. The limit switch 47, normally open while the hook 16 is in motion, is closed when the hook 16 reaches its original starting position because the lever 25 is arranged to depress the limit switch 47 at that point. The closing of the limit .switch 47 prepares the circuit for repetition of performance and allows the drive switch 46, already closed by continued pressure upon the adjusting .knob 35, to reactivate the drive cycle. It is thus seen that the closing of the limit switch 47 is a pre-requisite to the activation of the drive cycle.

The hydraulic circuit shown in Fig. 4 consists of a tank 71 provided with astrainer and breather 72. A pump 61 has its suction line from the reservoir or tank 71 and supplies the drive line 73 with fluid moving normally through the four-way hydraulically operated control valve 66 to force the vanes 69 of the rotating hydraulic cylinder 19 againstthe vane stop 22. The hydraulic components are located upon the top of the tank 71 which forms a mounting base and the tank 71 is located between the structural legs of the table 11 and made a part thereof. The hydraulic components in some applications might be remotely positioned, but the arrangement upon the tank 71 is compact and makes a self-contained unit. An adjustable relief valve 41 is interposed between the pump 61 and the control valve 66 in the drive line 73.

Operating pressures are adjusted by this means and a relief is provided preventing excessive pressures from damaging the pump .61. A pilot line 74 (broken lines in Fig. 4) is tapped off of thedrive line 73 which feeds through a solenoid operated spring return pilot valve 65. The energization of the solenoid 64 shifts the pilot valve 65 so as to direct operating fluid and pressure to the con- 'trol valve 66. -As the solenoid 64 is deenergized, the spring return 68 reverses the flow in the pilot lines which in turn reverses the drive lines through the control valve 66 and the rotation of the cylinder 19 directs the vanes 69 against the yanestop 22 so as to stop the machine in the original orkstarting position preventing over run. A pressure relief valve 70 in the return line relieves the pumping pressure on the returnstroke, because it is set -to .;provide only-enough pressure in the return line to .movethe hook '16 back to its original position.

. 6 Operation In operation, a shaft to be straightened 13 is mounted upon the shaft supports 12. The operator then rotates the shaft 13 upon its supports 12 and determines by means of dial' run-out indicators (not shown) the position of high points in the shaft. The high point in theshaft 13 is then positioned upwardly. The operator then pushes the master switch 51 feeding current to the motor starter 52. Then, by pushing the start button of the start-stop switch '58 in the 110 volt control circuit, the magnetic motor starter relay 59 closes the circuit through the motor starter 52 at contacts 59a, 59b and 59c which starts the motor 53, which, being ,drivably connected to the hydraulic pump 61, drives the hydraulic pump 61. Other contactor arms on the relay 59 close the circuit at contacts 59d and 59c. The pressure and fluid in the drive line 73 rotates the rotating hydraulic cylinder 19 to the start position against the vane stop 22. In this position the limit switch 47 is closed by the lever 25. The operator then draws the adjusting knob 35 forward and down bringing with it the pivotally mounted adjusting frame 34 to which 'is connected the spring clevis 39. The spring clevis 39is pivotally attached to the clevis mount 40 which is in turn attached to the pitman arm 17. In this manner, t'hehook 16 is pivoted on its eccentric 17a into position over the shaft to be straightened 13. Having noted the amount of run-out in the shaft 13, the operator selects a corrective deformation by rotating the adjusting knob 35. This rotation carries the cam 32 with it and necessarily predetermines the amount of gap 67 between the pin 28 and-the cam 32. The maximum amount of gap 67 .is equivalent to or proportional to the maximum movementof the hook .16 depending upon whether leverage is designed to equal or magnify the actual movement of the hook 16. The minimum amount of the gap 67 is equivalent to the zero movement of the hook 16. Thus, the operator .can select the desired amount of deflection in the shaft to be straightened 13 by the positioning of the cam 32. The operator having made his selection of deflection required forces the adjusting knob 35 and the connected frame 34 down so that the switch trip 45 closes the drive switch 46 putting the shaft straightener into the drive cycle. The rotating hydraulic cylinder 19'rotates the main shaft 18 and eccentric 17a so as to draw down the pitman arm 17 and hook 16 which engages the shaft to be straightened .13.

By .pre-selection of the positioning of thecam 32 the down movement of the hook 16 is limited by the upward movement of the pin 28 displacing the .cam 32 and pushing the switch trip 45 out of engagement with the drive switch 46. This opening of the drive switch 46 causes the de-energization of the solenoid 64 and the spring return 68 causes the reversal of the hydraulic circuit which returns the hook 16 to its originalposition (Fig. 2) closing the limit switch 47. Over-run of the hook 16 is prevented by the vanes 69 in-the cylinder 19 contacting vane stop 22. As the hook 16 returns to its original position the pin 28 recedes from engagement with the cam 32 and the drive switch 46 is closed by the continuing manual pressure downward upon theadjusting knob 35 by the operator. However, until the limit switch 47 is closed by the lever '25 when the hook 16 reaches its original position, the drive cycle cannot be repeated. The original position of the hook 16 being somewhat above the point of pressure engagement between the hook 16 and the shaft to be straightened 13, 'thereis a pause during which the shaft to be straightened 13 is relieved of deflecting pressure and a run-out indicator :(not shown) may be read to determine ,what deflection should be given the shaft to be straightened 13 on the next downpulling cycle. The deflection is varied appropri- 'ately by'the re-positioning of the cam 32-and the cycle is repeated; Similarly-a plurality'of these "units. may be mounted on a shaft 18 spacedlto engage a shaft to be straightened 13 at predetermined points. The electrical "circuitry requiredin such an arrangement requires merely a series connected sequence of drive switches 46. The "methods of operation using one hook 16hr aplurality thereof remains the same as disclosed.

The invention has been-describedasfshowinga commercial embodiment thereof. There has been no attempt to show any further 'adaptationsthereof and it is believed that this disclosure will enable those skilled in the art to adapt the invention as may be desired.

Iclaimy 1. In a shaft straightener, the combination including:

a table; supporting means for a shaft upon said table;

a table; supporting means for a shaft upon said table; means defining an opening in said table; a hook through said opening to engage said shaft; an eccentric vertically reciprocating said hook; a main shaft, said eccentric being on said main shaft; an hydraulic drive system, said main shaft operably connected to said hydraulic drive system;

and control linkage for predetermining the vertical downward movement of said hook including, a lever system operating eccentrically from the center of rotation of said main shaft; an electricalcircuit opened and closed by said lever system; andan hydraulic circuit activated by said electrical circuit. v

3. In a shaft straightener, the combination including: a table; supporting means for a shaft upon said table; means defining an opening in said table; a hook through said opening to engage said shaft; an eccentric vertically reciprocating said'hook; a main shaft; said eccentric on said main shaft; a rotating hydraulic cylinder; said main shaft operably connected to said rotating hydraulic cylinder; an hydraulic circuit providing drive means for said rotating hydraulic cylinder; and control means for predetermining the amount of downward movement of said hook.

4. In a shaft straightener, the combination including: a table; supporting means for a shaft upon said table; means defining an opening in said table; a hook through said opening to engage said shaft; an eccentric vertically reciprocating said hook; a main shaft, said eccentric on said main shaft; an hydraulic drive system, said main shaft operably connected to said hydraulic drive system; and a control linkage for predetermining the vertical downward movement of said'hook including a lever system operating eccentrically, from the end of said main shaft; an electrical circuit opened and closed by said lever system; and an hydraulic circuit activated by said electrical circuit.

5. In a shaft straightener, a control linkage for predetermining the amount of deformation applied to shafts including: a lever system moving in a correspondingly opposite direction from the deformation in said shafts; a

normally open drive switch; a solenoid energized by closing said drive switch; a manually operated switch trip shafts has ceased,'permittingeffective manual closure of said drive switch, and preparing the shaft" straightener 6. in a shaft straightener, a control linkage for pre- ,determiningthe' amount of deformation applied to shafts 10 including: -a lever system moving in a correspondingly opposite direction'from the deformation in said shafts;

'anormally'open drive switch; a solenoid energized by closing said drive switch; a manually operated switch trip closing said drive-switch, and provided with means varyingthe gap between said lever system and-said manually operatedswitch trip; a pin constituting a plunger and vertically moved by said lever'system; a normally open limit switch closed by 'said leversystem after deformation in 'said'shafts has ceased, permittingeffective manual closure of said drive switch and preparing the shaft straightener for repetitious performance; an hydraulic circuit provided With a solenoid operated spring return valve shifting to drive saidshaft straightenerwhen said solenoid is ener gized and causing reversal'thereof when said solenoid is de-energized. I

'7. In a shaft straightener, the combination including: a table; supporting means for a shaft upon said table; means defining a plurality of openings in said table; hooks through said openings to engage said shaft; a plurality of identical eccentrics reciprocating said hooks; a main shaft upon which said eccentrics are fixedly mounted; an hydraulic drive system, said main shaft dperably connected to said drive system; and control means for predetermining the amount of vertical downward movement of said hooks comprising, a lever system operating eccentrically,

from said main shaft; an electrical circuit opened and closed by said lever system; and an'hydraulic circuit activated by said electrical circuit.

8. In a shaft straightener, the combination including: a table; supportingmeans for a shaft upon said table; means defining a. plurality of openings in said table; hooks through said openings to-engage said shaft; a plurality of eccentrics vertically reciprocating .said hooks; a main shaft, said eccentricsfixedly attached to said main shaft; a rotating hydraulic cylinder; an hydraulic circuit providing drive means for said rotating hydraulic cylinder; and control means for, predetermining the amount of downward movement of said hooks.

9. In a shaftstraightener substantially as in claim 8,

'a control linkage for predetermining the vertical downward movement of said hooks including: a lever system operating eccentrically from the end of said main shaft; an electrical circuit opened and closed by said lever system; and an hydraulic'circuit activated by said electrical circuit. I 7

10. In a shaft straightener, a control linkage for {are determining the amount of corrective deformation applied to shafts including: eccentric means; a reciprocating member connected to said eccentric means for causing deformation in shafts to be straightened; a lever system operating from said eccentric means; a normally open drive switch; a solenoid energized by closing said drive switch; a manually operated switch trip closing said drive switch; meansmoved by said lever system and positioned so as to encounter said switch trip and open said drive switch; means associated'with said switch trip for varying the gap between said switch trip and said means moved by said lever system in accord with the selected amount of corrective deformation to be imparted to the shafts to be straightened; a normally open limit switch closed by said lever system to permit effective closure ofv said 'drive switch; an hydraulic'circuit provided with a solenoidoperated spring return valve shifting, to drive said eccentric when said solenoid is energized and cansing reversal when said solenoid is de-energized.

11. In a shaft straightener, a control linkage for predetermining the amount of corrective deformation applied to shafts including: an eccentric; a reciprocating member for causing deformation in shafts to be straightened and operative from said eccentric; a lever system connected to said eccentric; a normally open drive switch; a solenoid energized by closing said drive switch; a manually operated switch trip closing said drive switch; a pin reciprocated by said lever system and positioned so as to encounter said switch trip and open said drive switch; means associated with said switch, trip for varying the gap between said switch trip and said pin in accord with the selected amount of corrective deformation to be imparted to the shafts to be straightened; a normally open limit switch closed by said lever system after corrective deformation has ceased and permitting effective closure of said drive switch only after said eccentric has resumed a position imparting no deformation to the shafts to be straightened; an hydraulic circuit provided with a sole-- noid operated spring return valve shifting to drive said eccentric when said solenoid is energized and causing reversal when said solenoid is de-energized.

12. In a shaft straightener as described in claim 11, 25

wherein said means associated with said switch trip consists of: a cam which upon selective rotation varies the gap between said switch trip and said pin.

13. In a shaft straightener, a control linkage for predetermining the amount of corrective deformation applied to shafts including: an eccentric; a rotating hydraulic cylinder driving said eccentric; a reciprocating member connected to said eccentric for causing deformation in shafts to be straightened; a lever operably connected to said eccentric; a drive switch; a manually operated trip element selectively closing said drive switch and having a variably positioned cam means attached thereto; a pin reciprocated by said lever and positioned so as to engage said cammeans thereby opening said drive switch in accord with the movement of said lever; a limit switch engaging said lever at the full upper stroke of said eccentric; a solenoid energized by closing said drive switch only when said limit switch has been closed by said lever; and an hydraulic circuit energized to move said rotating hydraulic cylinder when said drive switch is closed and said limit switch is closed, and return when said drive switch is urged open by the engagement of said lever with the cam means of said trip element.

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